A technique for preventing occurrence of cracking in soldered areas (solder fillets) that connect tabs of a bus bar to a conductor of a printed board by forming a support member of a printed board (a circuit board) from a metallic material similar to that of the bus-bars has hitherto been known (see Patent Document 1).
As shown in FIG. 9, in an electric connection box using the technique, the tabs are caused to protrude from a flat bus bar 501 housed in a case, thereby connecting a conductor of the printed board 503 positioned above the flat bus bar 501 to the flat bus bar 501. Conductor connection tabs 505 and a board anchor tab 507 are caused to protrude from the flat bus bar 501. The conductor connection tabs 505 are inserted into respective first insertion holes 509 of the board, and the board anchor tab 507 is inserted into a second insertion hole 511. The conductor connection tabs 505 are soldered to the conductor of the printed board 503, and the board anchor tab 507 is also soldered to the printed board 503, thereby supporting the printed board 503.
A support member of the printed board 503 is formed from a metallic material analogous to that of the connection tabs of the flat bus bar 501, and the thus-formed support member is taken as the board anchor tab 507. Accordingly, the conductor connection tabs 505 to be connected to the conductor of the printed board 503 and the board anchor tab 507 that supports the printed board 503 can be made identical with each other in terms of a coefficient of thermal expansion. The conductor connection tabs 505 and the board anchor tab 507 are similarly inflated by thermal changes, whereby the printed board 503 secured to the board anchor tab 507 can be caused to follow inflation of the conductor connection tabs 505. Therefore, occurrence of cracking, which would otherwise arise when loads are imposed on soldered areas that connect the conductor connection tabs 505 to the conductor of the printed board 503, can be prevented.